Welcome to FT.

Given that you are on separate itins, I'd say it depends on how much of a worrier you are.

Under normal circumstances, you should easily make the connection; I've often driven home to SAN by 2.5 hours after my BA flights lands at LAX. If you miss the connection, UA will very likely take care of you, and if worst comes to worst the cost of a walkup 1-way on WN should be about 60 quid.

If you are comfortable with that, then stick with what you have. If you need certainty then I'd suggest switching to the later UA flight.